In broadest terms, the research objective is the elucidation of the mechanism of action of psychotropic drugs. In this connection, our group is interested in the possibility of gaining fuller insight into the role of adenosine 3',5'-monophosphate (cyclic AMP) and of guanosine 3',5'-monophosphate (cyclic GMP) in the central nervous system. There is now good evidence that these two compounds may mediate the effects of a variety of neurotransmitters on postsynaptic structures. In addition, recent evidence suggests that the effects of certain psychotropic drugs may be mediated through actions on the enzymes involved in cyclic AMP metabolism. Our aim is to identify, purify, and characterize the various enzymes in brain tissue responsible for the synthesis, action, and degradation of cyclic AMP and of cyclic GMP, and to provide further evidence that these cyclic nucleotides and their associated enzymes do indeed mediate the actions of various neurotransmitters and of various psychotropic drugs. It is our hope that these studies will contribute to a deeper understanding of the use of drug therapy in the treatment of mental illness and to improvemtnts in such therapy.